Norv isn't the only guy in America who can work with QBs. You don't give Norv a job that he is obviously not qualified to do, JUST for the opportunity for him to work with Romo.
What about David Lee for Romo's QB coach? Yes, I know he's now at Arkansas, but he would have stayed and worked with Garrett being the OC. You then could have hired a competent Defensive guy like Wade Phillips, (who at least has a winning record and several playoff appearances on his resume), as your HC. Romo credits Lee with his development, but Parcells chose to demote Lee this year and take him almost totally out of the picture so he could bring his buddy Chris Palmer back and make him the QB coach.